Method and system for performing a local switching of a local call

ABSTRACT

The present invention provides a method for implementing local call local switch, which includes that: a source MSC receives a handover request from a source BSS; the source MSC transfers a local reference to a destination BSS; and the destination BSS judges whether local switch can be triggered according to the received local reference, and executes the local switch if a judgment result is that the local switch can be triggered. The present invention further provides a system for implementing local call local switch, which includes a MSC and a BSS, wherein the MSC includes a MSC request module and a MSC processing module, and the BSS includes a BSS request module and a BSS processing module, so as to support for implementing the local call local switch in a handover scenario. The method and the system solve the problem of unsuccessful local switch due to BSS connecting multiple MSCs.

TECHNICAL FIELD

The invention relates to the communication field, and more specifically,to a method and a system for performing Local Call Local Switch (LCLS)in a circuit switched domain.

BACKGROUND OF THE RELATED ART

The circuit switch technology adopted by the mobile network such asGlobal System for Mobile communications (GSM) and Universal MobileTelecommunications System (UMTS) and so on, called as the CircuitSwitched (CS) domain, can provide the basic voice services and thesupplementary services based on voice services for users.

Some places in the world such as Africa, South America and South Asiaand so on, lack the fast and reliable transmission resources or have thehigh transmission cost, which brings difficulties in the network andservice deployment for operators. However, most of calls in the mobilenetwork are local calls in those places according to data statistics,and these calls are generated in the same Base Station System (BSS). Forthe local call, if the local switch technology (the voice data arelooped in BSS) is adopted, the transmission resources of the A interfacebetween BBS and the Mobile Switch Center (MSC) in the core network.

FIG. 1 is a schematic diagram of the traditional voice call, in whichthe User Equipment (UE) accesses BSS and MSC through the circuitswitched domain. When UE1 calls UE2, UE1 sends a call establishmentrequest to the its accessed MSC through BSS; MSC finds the called UE2according to the location information of the UE2 access, and notifiesBSS of establishing the radio bearers connecting UE1 and UE2, and thebearers of UE1 and UE2 are respectively established between BSS and MSC;the bearers at the both sides of MSC are looped to ensure the voicecommunication between UE1 and UE2.

FIG. 2 is a schematic diagram of the voice call adopting the local calllocal switch technology. Compared with FIG. 1, when receiving the callestablishment request of UE1, MSC judges whether UE1 and UE2 belong toone BSS according to a cell, and if UE1 and UE2 belong to the same oneBSS, MSC notifies BSS of performing the local switch; the bearer loopsof UE1 and UE2 are performed at the BSS side, which will save the bearerresource, i.e., bearer resource of the A interface between BSS and MSC.

FIG. 3 is a signaling flowchart adopting the local call local switchtechnology in FIG. 2, comprising the following steps of:

301, UE1 and UE2 initiate calling in the same BSS, and establishinterconnection through the MSC in the core network, and MSC allocatescircuit numbers or a call identifiers between BSS and MSC for callingUE1 and called UE2;

302, the called UE2 replies in the ringing state, and sends a calledreply message to MSC through BSS;

303, MSC sends the called reply message to the calling UE1, and notifiesUE1 of the call connecting;

304, MSC judges whether this call is a local call belonging to one BSSor not according to the current location information of the calling UE1and the called UE2;

305, if it is the local call belonging to one BSS, MSC sends the localswitch command message including the circuit numbers or the callidentifiers between BSS and MSC allocated for calling UE1 and called UE2in step 301 to BSS to notify BSS to perform the local switch;

306, BSS receives the local switch command message, associates with twoongoing communication sessions according to the circuit numbers or thecall identifiers of the calling and the called in the local switchcommand message, and loop their voice data bearers to implement toswitch the voice bearers within BSS;

307, BSS sends the local switch success message to MSC after the localswitch succeeding;

308, MSC notifies BSS of releasing the voice bearer connection betweenBSS and MSC after receiving the local switch success message, andreleases the bearer connection of the A interface.

With respect to the analysis in above steps, if the calling UE1 accessesMSC1 through BSS and the called UE2 accesses MSC2 through BSS in ascenario of BBS connecting multiple MSCs as shown in FIG. 4, althoughthe calling and the called initiates calling in the same BSS, thecalling and the called respectively access the different MSCs, therebyleading to whichever of MSC1 accessed by the calling UE1 and MSC2accessed by the called UE2 being unable to judge whether this call isthe local call according to location information of the calling and thecalled, and finally leading to a problem that the local call cannotperform the local switch.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method and a systemfor implementing local call local switch, to solve the problem ofunsuccessful local switch caused by the BSS connecting multiple MSCs.

The present invention is to provide a method for implementing local calllocal switch, which comprises:

a source MSC receiving a handover required message from a source BSS;

the source MSC transferring a local reference of an associated call to adestination BSS; and

the destination BSS judging whether local switch can be triggeredaccording to the received local reference, and executing the localswitch if a judgment result is that the local switch can be triggered.

Furthermore, in the above method,

the source MSC transfers the local reference to the destination BSS onlywhen a user meets a local switch condition.

Furthermore, in the above method, the user meeting the local switchcondition refers that the user does not have a session communicatingwith other users and a local switch user management strategy of anoperator is met.

Furthermore, in the above method, the local reference refers to a localreference allocated by a MSC at a calling side in a process ofestablishing a call, the allocated local references are different fordifferent calls, and the source MSC obtains and stores the localreference in the process of establishing the call.

Furthermore, in the above method, the step of the source MSCtransferring the local reference to the destination BSS comprises:

the source MSC transferring the local reference to a destination MSC;and

the destination MSC sending the local reference to the destination BSS.

Furthermore, in the above method, the step of the destination BSSjudging whether the local switch can be triggered according to thereceived local reference comprises:

the destination BSS finding whether there is a same local reference in adata area of the destination BSS or a corresponding data table accordingto the local reference after receiving the local reference sent by thedestination MSC, and if there is the same local reference, thedestination BSS determining that the local switch can be triggered.

Furthermore, in the above method, before the step of the destination BSSjudging whether the local switch can be triggered according to thereceived local reference, the method further comprises:

the destination BSS receiving a handover completion message sent by auser.

Furthermore, in the above method, after the step of the destination BSSexecuting the local switch, the method further comprises:

the destination BSS transferring an execution result to the source MSCand a destination MSC.

Furthermore, in the above method, the execution result includes ahandover completion message, and the handover completion messageincludes a local switch success indication.

Furthermore, in the above method, after the step of the destination BSSexecuting the local switch, the method further comprises:

after receiving the execution result, if the local switch succeeds, thesource MSC releasing a circuit with the source BSS; and

after receiving the execution result, if the local switch succeeds, thesource MSC releasing a circuit with the destination BSS.

The present invention further provides a system for implementing localcall local switch, and the system comprises a Mobile Switch Center (MSC)and a Base Station System (BSS), wherein the MSC comprises a MSC requestmodule and a MSC processing module, and the BSS comprises a BSS requestmodule and a BSS processing module, wherein

the MSC request module is configured to:

-   -   receive a handover required message sent by a source BSS;    -   select a destination MSC according to the handover required        message; and    -   transfer a local reference of an associated call to the        destination MSC;

the MSC processing module is configured to:

-   -   transfer a local reference of an associated call transferred by        a source MSC to a destination BSS; and    -   judge whether a correspondent user of a handover user meets a        local switch condition;

the BSS request module is configured to:

-   -   send a handover required message to the source MSC;

the BSS processing module is configured to:

-   -   receive the local reference of the associated call transferred        by the source MSC; and    -   judge whether local switch can be triggered, and execute the        local switch if a judgment result is that the local switch can        be triggered, and loop users at both sides to a local voice        bearer connection of the BSS.

Furthermore, in the above system, the MSC request module transfers thelocal reference only when the handover user meets the local switchcondition, wherein

the user meeting the local switch condition refers that the user doesnot have a session communicating with other users and a local switchuser management strategy of an operator is met.

Furthermore, in the above system, the local reference refers a localreference allocated by a source MSC in a process of establishing a call,and the allocated local references are different for different calls,

the MSC request module is further configured to: obtain and store thelocal reference in the process of establishing the call.

Furthermore, in the above system, the BSS processing module is furtherconfigured to:

find whether there is a same local reference in a data area of this BSSor a corresponding data table according to the local reference, and

if there is the same local reference, determine that the local switchcan be triggered.

Furthermore, in the above system, the BSS processing module is furtherconfigured to: receive a handover completion message sent by a user.

Furthermore, in the above system, the BSS processing module is furtherconfigured to: transfer an execution result to the source MSC and thedestination MSC after completing the local switch; wherein,

the execution result includes a handover completion message including alocal switch success indication.

Furthermore, in the above system,

the MSC request module is further configured to: release a circuit withthe source BSS after receiving the execution result;

the MSC processing module is configured to: release a circuit with thedestination BSS after receiving the execution result.

Compared with the related art, the invention provides a method and asystem for performing local call local switch, thereby solving theproblem of unsuccessful local switch due to BSS connecting multiple MSCsin the handover scenario.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of the traditional voice call;

FIG. 2 is a schematic diagram of the voice call adopting the local calllocal switch technology;

FIG. 3 is a signaling flowchart adopted the local call local switchtechnology in FIG. 2;

FIG. 4 is a schematic diagram of the scenario in which BSS connectsmultiple MSCs;

FIG. 5 is a flowchart of the embodiment for implementing the localswitch in the scenario that the calling user and the called user arelocated under different BSSs and the different MSCs according to thepresent invention;

FIG. 6 is a schematic diagram of the system for implementing local calllocal switch according to the present invention.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

Below the present invention will be further illustrated in detail incombination with drawings and embodiments.

FIG. 5 is a flowchart of the embodiment for implementing the localswitch in the scenario that the calling user and the called user arelocated under different BSSs and the different MSCs according to thepresent invention; the calling UE1 and the called UE2 respectivelybelong to the different BSSs and the different MSCs in the presentembodiment, wherein UE1 accesses MSC1 through BSS1, and UE2 accessesMSC2 through BSS2. In a call process of UE1 and UE2, UE1 hands over toBSS2, and BSS2 triggers the local switch according to the localreference. As shown in FIG. 5, wherein BSS1 is the source BSS, BSS2 isthe destination BSS, MSC1 is the source MSC, and MSC2 is the destinationMSC. The present embodiment comprises the following steps of:

501, UE1 and UE2 are calling, BSS1 decides to hand over the UE1 sessionto BSS2 according to radio measurement reports, and BSS1 sends thehandover required message to MSC1, and if BSS1 has stored the localreference generated in a the process of establishing the call, thehandover required message can include the local reference;

502, MSC1 receives the handover required message sent by BSS1, judgeswhether the current user UE1 meets the local switch condition, that is,judges whether UE1 currently has a session communicating session withother users, whether a local switch user management strategy of theoperator is met, and whether the monitoring point, i.e., the monitoringservice of MSC, is configured, and if UE1 simultaneously meets theconditions that there is not the session communicating with other userscurrently, the local switch user management strategy of the operator ismet, and the monitoring point, namely the monitoring service of MSC isconfigured, or, if UE1 at least meets the conditions that there is notthe session communicating with other users currently and the localswitch user management strategy of the operator is met, then the localswitch condition is met;

if the local switch condition is met, MSC1 selects the destination MSC2according to the address of the destination cell of the handover in thehandover required, and sends the handover request message including thelocal reference to MSC2;

503, MSC2 sends the handover request message to BSS2 to notify BSS2 toallocate the ground circuit and the air interface resources afterreceiving the handover request message, and the local reference fromMSC1 is forwarded in the handover request message;

504, BSS2 stores the local reference, allocates the air interface andthe ground circuit resources, allocates the handover numbers, andreturns the handover reply message to MSC2 after completing theallocation;

505, MSC2 returns the handover reply message including the handovernumbers allocated by MSC2 to MSC1;

506, MSC1 establishes the interoffice circuit bearer with MSC2 accordingto the handover number;

507, MSC1 sends the handover command to UE1 through BSS1 to notify UE1to hand over to BSS2;

508, UE1 sends a handover completion message to BSS2 after completingthe handover;

509, BSS2 judges whether the local switch can be triggered for users UE1and UE2 according to the local reference, wherein the judging method asfollows:

BSS2 perceives that there are two same local references, and findswhether there is a same local reference in a data area of BSS2 or acorresponding data table according to the local reference (i.e., thelocal reference from MSC1 is forwarded by MSC2 through the handoverrequest message) stored in step 504, and if there is the same localreference, then it is determined that the local switch can be triggered.

If users UE1 and UE2 can trigger the local switch, BSS2 executes thelocal switch, and UE1 and UE2 are looped to the voice bearer connectionof BSS,

BSS2 sends the handover completion message including the local switchsuccess indication to MSC2 after successfully executing the localswitch;

510, MSC2 sends the handover completion message including the localswitch success indication sent by BSS2 to MSC1;

511, BSS2 sends the local switch completion message to MSC2 at the sametime;

512, MSC1 records the local switch success indication after receivingthe handover completion message to notify BSS1 to clear the airinterface resources and release the ground circuit connecting with BSS1;and

513, MSC2 releases the ground circuit with BSS2.

In other embodiments, the step 511 is an optional step.

FIG. 6 is a schematic diagram of the system for implementing local calllocal switch according to the present invention. The system comprisesMSC and BSS, wherein MSC has a communication connection with BSS. TheMSC comprises an MSC request module and an MSC processing module, andthe BSS comprises a BSS request module and a BSS processing module,wherein

the MSC request module is configured to: receive a handover requiredmessage sent by a source BSS; select a destination MSC according to thehandover required message; and transfer local references of associatedcalls to the destination MSC;

the MSC processing module is configured to: transfer the localreferences of associated calls transferred by the source MSC to thedestination BSS; and judge whether a correspondent user of the handoveruser meets a local switch condition;

the BSS request module is configured to: send the handover requiredmessage to the source MSC;

the BSS processing module is configured to: receive the local referencesof associated calls transferred by the source MSC; and judge whether thelocal switch can be triggered, execute the local switch if the judgmentresult is that the local switch can be triggered, and loop users at bothsides to the voice bearer connection of this BSS;

thereby supporting for implementing the local call local switch in ahandover scenario.

Further, the MSC request module transfers the local reference only whenthe handover user meets the local switch condition, wherein the usermeeting the local switch condition refers that the user does not have asession communicating session with other users at present and the localswitch user management strategy of the operator is met.

Further, the local reference refers that the local reference allocatedby the source MSC in a process of establishing a call, and the allocatedlocal references are different for different calls,

and the MSC request module is further configured to: obtain and storethe local reference in the process of establishing the call.

Further, the BSS processing module is further configured to: findwhether there are the same local references in a data area of this BSSor a corresponding data table according to the local references; ifthere is the same local reference, it is determined that the localswitch can be triggered.

Further, the BSS processing module is further configured to: receive ahandover completion message sent by the user.

Further, the BSS processing module is further configured to: transfer anexecution result to the source MSC and the destination MSC aftercompleting the local switch; wherein,

the execution result includes the handover completion message includingthe local switch success indication.

Further, the MSC request module is further configured to: release thecircuit with the source BSS after receiving the execution result;

the MSC processing module is further configured to: release the circuitwith the destination BSS after the receiving the execution result.

Of course, the present invention can also have a variety of otherembodiments, and a person skilled in the art can make variouscorresponding changes and transformations according to the presentinvention without departing from the spirit and essence of the presentinvention, however, these corresponding changes and transformationsshould fall into the protection scope of appended claims in the presentinvention.

INDUSTRIAL APPLICABILITY

The invention provides a method and a system for implementing local calllocal switch, which solves the problem of unsuccessful local switchcaused by a BSS connecting multiple MSCs

1. A method for implementing local call local switch, comprising: asource Mobile Switch Center (MSC) receiving a handover required messagefrom a source Base Station System (BSS); the source MSC transferring alocal reference of an associated call to a destination BSS; and thedestination BSS judging whether local switch can be triggered accordingto the received local reference, and executing the local switch if ajudgment result is that the local switch can be triggered.
 2. The methodaccording to claim 1, wherein the source MSC transfers the localreference to the destination BSS only when a user meets a local switchcondition.
 3. The method according to claim 2, wherein the user meetingthe local switch condition refers that the user does not have a sessioncommunicating with other users and a local switch user managementstrategy of an operator is met.
 4. The method according to claim 1,wherein the local reference refers to a local reference allocated by aMSC at a calling side in a process of establishing a call, the allocatedlocal references are different for different calls, and the source MSCobtains and stores the local reference in the process of establishingthe call.
 5. The method according to claim 1, wherein the step of thesource MSC transferring the local reference to the destination BSScomprises: the source MSC transferring the local reference to adestination MSC; and the destination MSC sending the local reference tothe destination BSS.
 6. The method according to claim 5, wherein thestep of the destination BSS judging whether the local switch can betriggered according to the received local reference comprises: thedestination BSS finding whether there is a same local reference in adata area of the destination BSS or a corresponding data table accordingto the local reference after receiving the local reference sent by thedestination MSC, and if there is the same local reference, thedestination BSS determining that the local switch can be triggered. 7.The method according to claim 6, before the step of the destination BSSjudging whether the local switch can be triggered according to thereceived local reference, further comprising: the destination BSSreceiving a handover completion message sent by a user.
 8. The methodaccording to claim 1, after the step of the destination BSS executingthe local switch, further comprising: the destination BSS transferringan execution result to the source MSC and a destination MSC.
 9. Themethod according to claim 8, wherein the execution result includes ahandover completion message, and the handover completion messageincludes a local switch success indication.
 10. The method according toclaim 8, after the step of the destination BSS executing the localswitch, further comprising: after receiving the execution result, if thelocal switch succeeds, the source MSC releasing a circuit with thesource BSS; and after receiving the execution result, if the localswitch succeeds, the source MSC releasing a circuit with the destinationBSS.
 11. A system for implementing local call local switch, comprising aMobile Switch Center (MSC) and a Base Station System (BSS), wherein theMSC comprises a MSC request module and a MSC processing module, and theBSS comprises a BSS request module and a BSS processing module, whereinthe MSC request module is configured to: receive a handover requiredmessage sent by a source BSS; select a destination MSC according to thehandover required message; and transfer a local reference of anassociated call to the destination MSC; the MSC processing module isconfigured to: transfer a local reference of an associated calltransferred by a source MSC to a destination BSS; and judge whether acorrespondent user of a handover user meets a local switch condition;the BSS request module is configured to: send a handover requiredmessage to the source MSC; the BSS processing module is configured to:receive the local reference of the associated call transferred by thesource MSC; and judge whether local switch can be triggered, and executethe local switch if a judgment result is that the local switch can betriggered, and loop users at both sides to a local voice bearerconnection of the BSS.
 12. The system according to claim 11, wherein theMSC request module transfers the local reference only when the handoveruser meets the local switch condition, wherein, the user meeting thelocal switch condition refers that the user does not have a sessioncommunicating with other users and a local switch user managementstrategy of an operator is met.
 13. The system according to claim 12,wherein the local reference refers a local reference allocated by asource MSC in a process of establishing a call, and the allocated localreferences are different for different calls, the MSC request module isfurther configured to: obtain and store the local reference in theprocess of establishing the call.
 14. The system according to claim 13,wherein the BSS processing module is further configured to: find whetherthere is a same local reference in a data area of this BSS or acorresponding data table according to the local reference, and if thereis the same local reference, determine that the local switch can betriggered.
 15. The system according to claim 11, wherein the BSSprocessing module is further configured to: receive a handovercompletion message sent by a user.
 16. The system according to claim 11,wherein the BSS processing module is further configured to: transfer anexecution result to the source MSC and the destination MSC aftercompleting the local switch; wherein, the execution result includes ahandover completion message including a local switch success indication.17. The system according to claim 16, wherein the MSC request module isfurther configured to: release a circuit with the source BSS afterreceiving the execution result; the MSC processing module is configuredto: release a circuit with the destination BSS after receiving theexecution result.